Synthesis, structure, DNA binding, cleavage and biological activity of cobalt (III) complexes derived from triethylenetetramine and 1,10 phenanthroline ligands

Abstract

The cobalt (III) complexes, [Co(trien)(phen)] (ClO4)2Cl, (1), [Co(trien)(phen)](NO3)3, (2) (where trien=triethylenetetramine, phen=1,10-phenanthroline) has been synthesized and characterized by Infra-red, UV–Vis, ESI-MS and elemental analysis methods. Complex 1 was structurally characterized by single crystal X-ray crystallography. It was crystallized in a triclinic system with space group P1¯, a=7.797(10)Å, b=10.6584(2)Å, c=14.889(3)Å, α=96.83(10)°, β=96.16(10)°, and γ=98.88(10)°. The cobalt atom assumes a distorted octahedral geometry by coordinating to 6 nitrogen atoms from four triethylenetetramine and two 1,10-phenanthroline ligands. The binding of this cobalt (III) complex with calf thymus DNA (CT-DNA) was investigated by UV–Vis absorption, fluorescence spectroscopic, cyclic voltammetric and viscosity techniques. Also, the interactions of pBR322 DNA with these cobalt (III) complexes were studied using the gel electrophoresis method. The thermal denaturation and viscosity binding data advocates that the cobalt (III) complexes interact with DNA by groove binding. When compared to complex 2 complex 1 has more potential to the kill human liver cancer cell as revealed by the MTT assay. The cobalt (III) complexes screened for their activities in vitro on common bacteria and fungi and exhibit antimicrobial activities.